Intermix Layer for Void-Free Metal Reflow in Trenches
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Solution Overview
Problem
Conventional reflow processes for filling trenches/vias in semiconductor devices often result in voids, particularly for smaller form factors, due to challenges in scaling down interconnects.
Innovation Solution
A method involving chemical vapor deposition (CVD) and physical vapor deposition (PVD) processes to deposit metallic materials, forming a seed layer and an intermix layer within features on a substrate, followed by heating to reflow the material, which improves filling and reduces voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional reflow processes are used to fill trenches/vias, then the process is simple and fast, but voids are formed within the trenches/vias for smaller form factors
Solution Approach 1:
The filling process is divided into multiple stages: initial deposition of metallic material, formation of seed layer, creation of intermix layer through etching, and controlled reflow. This segmentation allows each stage to be optimized independently, improving overall filling quality while managing process complexity through systematic breakdown of the manufacturing sequence.
Solution Approach 2:
The intermix layer is formed in advance before the final reflow process. This preliminary action of creating an intermix layer between the metallic material and surrounding structures prepares the interface for better material flow during reflow, preventing void formation while maintaining process control.
2Manufacturing precision
If the reflow temperature is increased to improve material flow, then voids are reduced, but excessive intermixing and loss of material definition occur
Solution Approach 1:
The reflow temperature is precisely controlled within a specific range to achieve optimal material flow without excessive intermixing. By adjusting this critical parameter, the process achieves complete void elimination while preserving the definition and integrity of the metallic material structures.
Solution Approach 2:
The intermix layer acts as an intermediary between the metallic material and the surrounding dielectric or barrier layers. This intermediate layer facilitates controlled material interaction during reflow, enabling smooth material flow to fill voids while preventing uncontrolled intermixing that would blur material boundaries.
3Volume of moving object
If smaller trench/via dimensions are used to achieve smaller form factors, then device size is reduced, but void formation increases during filling
Solution Approach 1:
The process creates locally optimized conditions within each trench and via structure. The intermix layer formation and controlled reflow are tailored to the specific dimensions and geometry of each feature, ensuring complete filling even in the smallest structures while maintaining uniform quality across the entire device.
Solution Approach 2:
The solution addresses the three-dimensional filling challenge by introducing temporal dimension through multi-stage processing and spatial dimension through lateral material flow control. The intermix layer enables material to flow laterally and vertically in a controlled manner, completely filling high aspect ratio trenches and vias without voids.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively fills features by forming an intermix layer that enhances the reflow process, reducing voids and improving the filling of trenches/vias, especially in smaller form factors.
Implementation Method 1
depositing a first metallic material on the substrate and within a feature disposed in the substrate in a first process chamber via a chemical vapor deposition (CVD) process at a first temperature
Implementation Method 2
depositing a second metallic material on the first metallic material in a second process chamber at a second temperature and at a first bias power to form a seed layer
Implementation Method 3
etching the seed layer in the second process chamber at a second bias power greater than the first bias power to form an intermix layer
Implementation Method 4
heating the substrate to a third temperature greater than the second temperature, causing a reflow of the second metallic material within the feature
Data Source
AI summary
Methods and apparatus for filling features on a substrate are provided herein. In some embodiments, a method of filling features on a substrate includes: depositing a first metallic material on the substrate and within a feature disposed in the substrate in a first process chamber via a chemical vapor deposition (CVD) process at a first temperature; depositing a second metallic material on the first metallic material in a second process chamber at a second temperature and at a first bias power to form a seed layer of the second metallic material; etching the seed layer in the second process chamber at a second bias power greater than the first bias power to form an intermix layer within the feature comprising the first metallic material and the second metallic material; and heating the substrate to a third temperature greater than the second temperature, causing a reflow of the second metallic material.